LONDON/FREETOWN (Reuters) - A British national living in Sierra Leone has tested positive for Ebola, the first Briton to fall victim to the deadly disease that has spread across the West African region since March, the Department of Health said on Saturday.

The World Health Organisation (WHO) estimates that the current Ebola epidemic - the world's worst ever with 1,427 documented deaths - will likely take six to nine months to halt.

Some aid organisations, including medical charity Medecins Sans Frontieres, have warned that the outbreak, which began in Guinea before spreading to Sierra Leone, Liberia and Nigeria, is now out of control.

The WHO conceded on Friday that the hiding of victims and the existence of "shadow zones" where medics cannot go has concealed the true scale of the epidemic.

Britain's Deputy Chief Medical Officer John Watson confirmed a British national was among those suffering from Ebola and said medical experts were assessing the situation in Sierra Leone to ensure appropriate care was provided.

"The overall risk to the public in the UK continues to be very low," Watson said in a statement.

No further details about the British national were immediately available, and it was not known whether there were plans to evacuate the patient.

Ebola, which is passed on by direct contact with the bodily fluids of infected persons, strikes hardest at healthcare providers and caregivers who work closely with those infected. And dozens of local doctors and nurses have died from the virus in recent months.

Two American aid workers, who contracted Ebola in neighbouring Liberia and were then evacuated, recovered from the disease and were released from a hospital in the United States earlier this week.

Fear, stigma and denial have led many families to hide their infected loved ones from health officials. In other instances, patients have been forcibly removed from treatment facilities and isolation centres, creating the risk of the disease's further spread.

Under-reporting of Ebola cases has been a problem particularly in Liberia and Sierra Leone, currently the two countries hardest hit by the virus.

Lawmakers in Sierra Leone on Friday voted overwhelmingly in favour of making the harbouring of those infected with Ebola a crime carrying a punishment of two years in prison.

As the outbreak has spread across borders from its initial epicentre, governments in the region have introduced increasingly strict travel restrictions.

The government of Ivory Coast announced late on Friday that it had closed its land borders Guinea and Liberia to try to prevent the virus from crossing onto its territory.

Ivory Coast, French-speaking West Africa's largest economy and the world's top cocoa producer, had previously imposed a ban on flights to and from Sierra Leone, Liberia and Guinea.

Liberia's Nimba County, which shares a border with Ivory Coast, has seen the number of Ebola cases balloon in recent weeks. According to Moses Massaquoi, the head of Ebola case management at Liberia's health ministry, 65 cases including 25 confirmed patients have now been reported there.

"The number of cases in Nimba has spiked recently and it is now an area of concern," Massaquoi told Reuters.

The WHO does not recommend travel or trade restrictions for countries affected by Ebola, saying such measures could heighten food and supply shortages. But residents of Ivory Coast's commercial capital Abidjan voiced support for the government's decision.

"I don't think simply closing the border is enough. We need to go even further," said Romaric Kouadio, a laboratory technician.

The Philippines on Saturday ordered 115 soldiers to return home from peacekeeping operations in Liberia due to the outbreak there.

Brussels Airlines, Belgium's largest carrier, said on Saturday it was cancelling flights to the capitals of Guinea, Liberia and Sierra Leone for Sunday and Monday due to new restrictions put in place by Senegal's aviation authority.

The company's flight to Freetown on Friday was denied permission to land for a crew change at the airport in Senegal's capital Dakar, and the plane was forced to continue on to Casablanca for an unscheduled landing.

Senegal, West Africa's humanitarian hub, had announced earlier in the day that it was banning all flights to and from countries affected by Ebola. It also blocked a U.N. aid plane from landing in Dakar.